On critical control measurements (main steam, feedwater) is it good practice for a DP flow xmtr and a gage xmtr to share the same (either HP or LP) impulse line before teeing take place near the xmtrs?
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A single instrument sensing line should not be used to perform both a safetyrelated function and a non safety-related function unless the following can be shown:
a. The failure of the common sensing line would not simultaneously
1. cause an action in a non-safety-related system that results in a plant condition requiring protective action and
2. also prevent proper action of a protection system channel designed to protect against the condition.
Tubing system should be such that the failure of non safety impulse line/tubing should not affect the reading of safety system.
